Cho \(\int\limits_{1}^{3}{f\left( x \right)\text{d}x}=-5, \int\limits_{1}^{3}{\left[ f\left( x \right)-2g\left( x \right) \right]\text{d}x}=9\). Tính \(\int\limits_{1}^{3}{g\left(...

* Hướng dẫn giải

Ta có \(\int\limits_{1}^{3}{\left[ f\left( x \right)-2g\left( x \right) \right]\text{d}x}=9\Leftrightarrow \int\limits_{1}^{3}{f\left( x \right)\text{d}x-2}\int\limits_{1}^{3}{g\left( x \right)\text{d}x}=9\Leftrightarrow -5-2\int\limits_{1}^{3}{g\left( x \right)\text{d}x}=9\)

\(\Leftrightarrow \int\limits_{1}^{3}{g\left( x \right)\text{d}x}=-7\).